303I: Final Drive Fundamentals & Service Flashcards
Identify two functions of a final drive system.
- Torque multiplication - Reduction configuration
- Absorb shock loads imposed on the powertrain due to operation in harsh off-road environments. Abuse
303I Pg. 2
Planetary final drive systems can be identified as ______ mounted or _______ mounted.
Inboard & Outboard
303I
Explain what is meant by the term outboard mounted, when describing planetary final drive systems.
The location of the planetary final drive system.
An outboard mounted planetary final drive is positioned at the wheel or sprocket as opposed to being mounted to each side of the bevel gear case.
303I Pg. 3
List one disadvantage of an inboard mounted final drive.
Size of the output shaft must increase substantially to manage the increased output torque of the final drive.
303I Pg. 6
The final drive housings on many motor graders act very similar to which component of an on-highway truck?
Walking beam
303I Pg. 8
On wheeled equipment, the most common gearing configuration used in single planetary final drives is a:
First speed reduction
303I Pg. 11
Chain drives are typically simpler in design and more cost effective to produce and operate than comparable gear boxes. (T/F)
True
303I Pg. 13
The inverter phase module on an AC drive system converts ______ to ______ for the traction motors when in propel mode.
DC to AC for the traction motors in propel mode
303I Pg. 22
The choppers in an AC drive system control the amount of current flow through the:
Resistive grids during dynamic braking
303I Pg. 22
A low DC bus voltage must be verified prior to working in which areas of an AC drive system?
All areas which are exposed to high voltage
303I Pg. 27
What are the two layers of gloves that must be worn when working on high voltage drive systems?
Rubber inner and leather outer gloves
Rated for a minimum 5000 volts
303I Pg. 29
What is the minimum safe working distance for a technician wearing full PPE when testing an AC drive system for high voltage?
30 cm / 12” from any conductive component until the voltage is confirmed to be less than 50 Volts DC
303I Pg. 29
Tracked equipment may be equipped with the following 4 types of final drive systems:
- Spur gear single reduction
- Spur gear double reduction
- Planetary gear single reduction
- Planetary gear double reduction
303I Pg. 30
When a planetary final drive is used on a tracked machine, the last gear reduction is between the drive sprocket and the track chain. (T/F)
False
303I
How are final drive components typically lubricated?
- Splash lubrication
Filtering By:
- No filtering (maybe a magnetic drain plug to catch metallic particles)
- Remote filter cart used during scheduled maintenance
- Onboard pressure lubrication & filter system
303I Pg. 38
AC drive systems usually have higher _______ then DC systems.
Efficiency
303I Pg. 16
Why do AC drive systems use solid-state inverters without any moving parts?
Solid state inverters are faster and more responsive
303I Pg. 16
Are AC drive machines generally more or less fuel efficient than mechanical drive machines?
More efficient
303I Pg. 17
What are some advantages of AC drive over mechanical drive?
- Long component lifespans
- Relatively maintenance free
- The ability to run the diesel engine at a constant speed
- No gear shift shock increases overall drivetrain life
- Engine and generator are often exchanged as a unit which limits downtime
- Great retarding abilities, saving mechanical brakes
- Less oil consumption over their lifespan due to the lack of the transmission torque converter and differential oils
303I Pg. 17
The brushless generator is an electro mechanical device that converts _____ energy from the diesel engine into _______ energy
Mechanical to electrical
What are the five functions of the main control group?
1) Converts three phase AC from the generator into DC bus voltage through rectifier assemblies.
2) Converts DC bus voltage to three phase AC for the wheel traction motors through phase modules.
3) Protects the phase modules and the dynamic retarding inverter by using capacitors to filter and store DC bus voltage as well as absorb any transient DC voltage spikes.
4) Controls the amount of DC bus voltage flowing to the dynamic retarding grids by operating the high-voltage contactors and the retarder chopper
5) Regulates the speed of three phase AC retarding grid blower motor by controlling the operation of the dynamic retarding inverter
303I Pg. 19
During propel mode, how do the inverters and AC drives control system control the speed and torque of the traction motors?
By using a PWM signal to convert DC bus voltage into variable three phase AC for the wheel traction motors.
303I Pg. 20
Which configuration of planetary final drive allows for smaller power train components upstream? (Inboard or Outboard)
Outboard
303I Pg. 4
An advantage of the outboard planetary final drive is ease of maintenance and servicing. (T/F)
True.
